Re: [PATCH net-next 4/7] ixgbe: protect vxlan_get_rx_port in ixgbe_service_task with rtnl_lock

[Alexander Duyck]

On Mon, Apr 18, 2016 at 12:19 PM, Hannes Frederic Sowa
 wrote:
> vxlan_get_rx_port requires rtnl_lock to be held.
>
> Cc: Jeff Kirsher 
> Cc: Jesse Brandeburg 
> Cc: Shannon Nelson 
> Cc: Carolyn Wyborny 
> Cc: Don Skidmore 
> Cc: Bruce Allan 
> Cc: John Ronciak 
> Cc: Mitch Williams 
> Signed-off-by: Hannes Frederic Sowa 
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 2976df77bf14f5..b2f2cf40f06a87 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct 
> *work)
> return;
> }
>  #ifdef CONFIG_IXGBE_VXLAN
> +   rtnl_lock();
> if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
> adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
> vxlan_get_rx_port(adapter->netdev);
> }
> +   rtnl_unlock();
>  #endif /* CONFIG_IXGBE_VXLAN */
> ixgbe_reset_subtask(adapter);
> ixgbe_phy_interrupt_subtask(adapter);
> --
> 2.5.5
>

Would it be possible to only take the lock inside of the conditional
statement?  There isn't really any need to be holding the rtnl_lock to
check the adapter flag.

- Alex

Re: [PATCH net-next 4/7] ixgbe: protect vxlan_get_rx_port in ixgbe_service_task with rtnl_lock

[Alexander Duyck]

On Fri, Jun 10, 2016 at 2:17 PM, Eric Dumazet  wrote:
> On Mon, 2016-04-18 at 21:19 +0200, Hannes Frederic Sowa wrote:
>> vxlan_get_rx_port requires rtnl_lock to be held.
>>
>> Cc: Jeff Kirsher 
>> Cc: Jesse Brandeburg 
>> Cc: Shannon Nelson 
>> Cc: Carolyn Wyborny 
>> Cc: Don Skidmore 
>> Cc: Bruce Allan 
>> Cc: John Ronciak 
>> Cc: Mitch Williams 
>> Signed-off-by: Hannes Frederic Sowa 
>> ---
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
>> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> index 2976df77bf14f5..b2f2cf40f06a87 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct 
>> *work)
>>   return;
>>   }
>>  #ifdef CONFIG_IXGBE_VXLAN
>> + rtnl_lock();
>>   if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
>>   adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
>>   vxlan_get_rx_port(adapter->netdev);
>>   }
>> + rtnl_unlock();
>>  #endif /* CONFIG_IXGBE_VXLAN */
>>   ixgbe_reset_subtask(adapter);
>>   ixgbe_phy_interrupt_subtask(adapter);
>
> Although there might be a deadlock with a concurrent
> cancel_work_sync(>service_task);  from ixgbe_remove()

I don't think we are holding the rtnl_lock when that is called.  The
ixgbe_remove function is a PCI function.  The ixgbe_close routine is
the one called with the rtnl_lock held.

- Alex

Re: [PATCH net-next 4/7] ixgbe: protect vxlan_get_rx_port in ixgbe_service_task with rtnl_lock

[Eric Dumazet]

On Mon, 2016-04-18 at 21:19 +0200, Hannes Frederic Sowa wrote:
> vxlan_get_rx_port requires rtnl_lock to be held.
> 
> Cc: Jeff Kirsher 
> Cc: Jesse Brandeburg 
> Cc: Shannon Nelson 
> Cc: Carolyn Wyborny 
> Cc: Don Skidmore 
> Cc: Bruce Allan 
> Cc: John Ronciak 
> Cc: Mitch Williams 
> Signed-off-by: Hannes Frederic Sowa 
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 2976df77bf14f5..b2f2cf40f06a87 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct 
> *work)
>   return;
>   }
>  #ifdef CONFIG_IXGBE_VXLAN
> + rtnl_lock();
>   if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
>   adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
>   vxlan_get_rx_port(adapter->netdev);
>   }
> + rtnl_unlock();
>  #endif /* CONFIG_IXGBE_VXLAN */
>   ixgbe_reset_subtask(adapter);
>   ixgbe_phy_interrupt_subtask(adapter);

Although there might be a deadlock with a concurrent
cancel_work_sync(>service_task);  from ixgbe_remove()